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O. E. SPEAR.

ADDING MACHINE.

No. 106,881. Patented Aug. 30, 1870.

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CHARLES E. SPEAR, OF GARDINER, MAINE, ASSIGNOR TO EUGENE HUM- A PHREY, OF CHELSEA, MASSACHUSETTS.

Letters Patent No. 106,881, dated August 30, 1870.

IMPROVEMENT 111 ADDING-MACHINE.

To all whom it may conccrn:

Be it known that I, Gnsnnns E. Srusn of Gar-diner, in the county of Kennebec and State of Maine, have invented anew and improved Instrument for Adding Numbers; and I do hereby declare that the follow ing is a full and exact description thereof, reference being had to the accompanying drawing and to the letters of reference marked thereon.

My inventionconsists of a very simple and reliable adding-instrument, by the use of which the rniud is relicvedfiom the tiresome process of adding long columns of figures, and such additions are more acculately and. speedily accomplished.

;The instrument is constructed of a board or bedprece of any suitable material, in form of a parallelogram, and having six longitudinal grooves on each side.

iln these grooves are fitted sliding bars, those on the upper side being perforated, and numbered on their under sides from right to left, as indicated in Figure 2, andhaving pins or stops, a, projectingupward.

The slides on" the under side are perforated, and numbered on their upper sides from left to. right, as indicated in Figure 3.

Figures 4 and 5 are opposite-end views of the grooved board in which the slides operate.

Figure 1' represents a top view of the adding-insomment, with its slides in proper position to commence adding a column of H ures.

The upper or addiifg-slides are kept in the grooves by the traverse-caps A A, and the under or carryingslides are kept in their'grooves by a back covering the ,crrtire under side of the instrument, and shown in Figure 6.

At the left end of the instrument, the upper and under grooves open into each other, and through the circular apertures are seen the ciphers on the carrying-slides.

Between the caps A A are seen the adding-slides, and on theboard, between the grooves in which these .slides operate, are repeated the figures from 1 to 9,

inclusive.

Opposite the its stand the pins or stops on the adding-slides, while opposite each of the other figures is a perforation.

The dotted circular lines o b, in the right-hand cap A, indicate apertures through the grooved board and the back, as shown in fig. 6, through which the cipherson the under side of the adding-slides are seen, and through which the. results of additions are read.

The dotted lines d ll, in the left-hand cap A, are downward projections or flangesou the edge of said cap, which enter the upper grooves, and serve as a stop to the adding-slides when moved to the left, while the stop-pins on said slides limit their morernent in the opposite direction by striking against the edge of the right-hand cap A.

The under or drrrying-srrues are stopped in the lefthanddircctiou by an end piece fastened across the grooves, while do their movement to the right they are checked by projections intotheir grooves from the back, as indicated by dotted lines a n, fig. 6.

The dotted lines o 0 represent the slots in the grooved board, through which the pointer, Figure 7, is allowed to pass in its left-hand movements when the addition anrounts to more than nine, and enter the perforations of the marrying-slides, and move them simultaneously with the adding-slides. Thus, if we wish to add the two units 9 and (i, we move the pin opposite 9 in the upper line of figures to the right until it comes in contact with the edge of the cap A; then we insert the pointer in the perforation opposite the figure 6, and, with a slight downward pressure, more it to the left as far as it will go; when opposite the figure 9, it will drop through the slot 0 into a perforation in the carrying-slide, and move said .slide alougonenumber, when, as a. result of the addition, will appear at b on the back of the instrument the figure 5, while in the opposite aperture on the face of the instrument will appear the number to be carried to the tens column, (1.)

After completing one addition, the instrument is adjusted for use again by sirnpiy moving all the adding=slides to the left as far as they will go, which will bring the pins on the same opposite the 9s, as shown in fig. 1. The carrying-slides are then moved to the ight by inserting the pointer in the openings m m, and pressing it against the ends of said slides, and thus moving them back to the position, with their ciphers in-the circular apertures, as shown in fig. 1.

.To'add tens, hundreds, thousands, &c., it is simply necessary to move the slides representing tens, hurrdreds', and so on, in the manner described. Thus, six colurns of figures-(and more by increasing the number of slides) may be added at a time, including dollars and cents, and amounting to millions, with perfect acra-cy, and without taxing the mind with the carrying numbers from one column to the next higher. Tire numbers to be carried will stand before the operator in their respective apertures on the left, and need not be carried to the next columns till the other additions are completed. The result of the additions, when completed, will appearin the apertures on the back of the instrument.

The slides are kept in position by friction applied in any convenient manner, and which may be so applied asto be adjustable, and enable the operator to clamp said slides firmly in their grooves in any desired position, when the result of an addition is required to be kept for a tiurc.

The ir'rstrruuent is very simple in construction, and easily understood and operated. It is positive and accurate in its operation, as every movement or change is directly com-rolled and impelled by the hand of the opemtm, and not left to depend, in any degree, on

the automatic action of springs, or any mechanism,

whereby the liability to inaccuracy arising from the wear and consequent derangement of such devices is wh'olly'avoided, and its simple carrying principle secures the greatest mathematical exactness with the least mental labor.

What I claim as my invention, and desire to secure by Letters Patent, is-

, 1. The arrangement of two series of slides in a double-grooved board or bed, with slots 0 a through the same, whereby a carrying and adding-slide may wear 

